1. Field of the Invention
The present invention relates to a mobile communication terminal, and in particular to a DBDM (dual band dual mode) terminal supporting different packet frame modes.
2. Background of the Related Art
Due to the expanding usage range of mobile stations and increasing demand for high speed data communication, there has been a limit for supporting various data communication services with present CDMA (code division multiple access) networks as second generation wireless communication networks.
Accordingly, WCDMA (wideband code division multiple access) networks have been introduced as a third generation communication network for supporting various data communication services and high speed data communication. However, because the third generation communication network has been presently installed by way of example, a DBDM (dual band dual mode) terminal has been developed that uses the third generation communication network in an area in which a pertinent third generation communication network is installed and uses the existing second generation communication network in the third generation communication network-installed area.
The DBDM terminal may include a CDMA modem chip, a WCDMA modem chip and a video chip. More specifically, the terminal may include a total of three processors and an interface among the processors.
The video chip performs a function of a master control program for controlling a UI (user interface) (not shown) of a mobile station and includes applications of packet data services such as a VOD (video on demand), a WAP (wireless application protocol) and a MMS (multimedia message service).
In the CDMA modem chip, communication protocols (TCP/UDP/IP/PPP) for processing a CDMA protocol stack and packet data are provided. In addition, in order to interwork with application of a packet data service of the video chip, a socket API (application program interface) is mounted onto a TCP/UDP superior layer.
In CDMA networks, data communication is performed between a terminal and a base station by using PPP (point to point protocol) frames. Accordingly, in the case of performing communication by using PPP frames in the CDMA network, the DBDM terminal performs data communication by using the CDMA modem chip.
When the DBDM terminal receives data from the CDMA network, the CDMA modem chip processes PPP frames received from the CDMA network into IP packets according to the built-in communication protocols (TCP/UDP/IP/PPP) and transmits the IP packets to the video chip. In addition, when the terminal transmits data in the CDMA network, the CDMA modem chip converts the IP packets received from the video chip into PPP frames according to the built-in communication protocols (TCP/UDP/IP/PPP) and transmits them through the CDMA network.
In the WCDMA modem chip, communication protocols TCP/UDP/IP/PPP) for processing the WCDMA protocol stack and packet data are provided. In addition, similar to the CDMA modem chip, in order to interwork with applications of the packet data service of the video chip, a socket API (application program interface) is mounted onto a TCP/UDP superior layer.
In the case of performing data communication in the WCDMA network, both PPP and IP (internet protocol) frames are supported between a terminal and a base station. In the WCDMA network, because it is appropriate to communicate with IP frames in performance and expense aspects, communication is generally performed by using IP frames, as occasion demands, and IP frames and PPP frames are mutually converted and used.
In the above-mentioned DBDM terminal, because data communication protocols exist in a modem chip supporting each network and different protocols are used according to the WCDMA and CDMA networks, when a packet data service is implemented, an additional interface for interworking a socket with a modem chip according to each network is required. In addition, because it is difficult to interwork applications of all packet data services directly with a socket, performance of a terminal may be lowered, and all communication protocols of the WCDMA modem chip and the CDMA modem chip have to be debugged when the terminal has a problem.